بسمه الله الرحمن الرحیم - PowerPoint Presentation

Slide1

بسمه الله الرحمن الرحیم

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All open operative procedures on the abdominal aorta and its major branches require

Large incisions and extensive dissection

Clamping and unclamping of the aorta or its major branches

Varying duration of organ ischemia-reperfusion,

Significant fluid shifts and temperature fluctuations

And activation of

neurohumoral

and inflammatory responses

Slide10

Abdominal Aortic Aneurysm

Occur frequently in elderly men

Incidence approaching

8

%

RISK FACTORS :

Age

Smoking

Family history

of

abdominal aortic aneurysm

Atherosclerotic disease

Slide11

PATHOGENESIS

Adventitial

elastin

degradation (

ELASTOLYSIS

) a hallmark of abdominal aortic aneurysm formation, may be the primary event.

Chronic Inflammation

is a prominent feature of abdominal aortic aneurysms and probably plays a fundamental role in the destruction of connective tissue in the aortic wall

Slide12

PATHOGENESIS

Rare causes of

abdominal aortic aneurysm:

Trauma

Mycotic

infection

Syphilis

Marfan’s

syndrome

Slide13

The natural

history of abdominal aortic

aneurysmal

disease is

one of progressive enlargement and ultimate rupture and death

.



Slide14

MORTALITY

For ruptured abdominal aortic aneurysms,

perioperative

mortality

has not changed significantly over the last 4

decades and

remains nearly

50%

, with few exceptions.

If

one takes

into consideration

patients with rupture who die

before

reaching

a hospital

, the overall mortality rate after rupture may very

well exceed

90

%

Slide15

Physiologic Changes with Aortic

Cross-Clamping

Hemodynamic Changes

↑

Arterial blood pressure above the clamp

↓

Arterial blood pressure below the clamp

↑

Segmental wall motion abnormalities

↑

Left ventricular wall tension

↓

Ejection fraction

↓

Cardiac output†

↓

Renal blood flow

↑

Pulmonary occlusion pressure

↑

Central venous pressure

↑

Coronary blood flow

Slide16

Physiologic Changes with Aortic

Cross-Clamping

Metabolic Changes

↓

Total-body oxygen consumption

↓

Total-body carbon dioxide production

↑

Mixed venous oxygen saturation

↓

Total-body oxygen extraction

↑

Epinephrine and

norepinephrine

Respiratory alkalosis

Metabolic acidosis

Slide17

Therapeutic Interventions

Afterload

reduction

Sodium

nitroprusside

Inhaled anesthetics

Amrinone

Shunts and aorta-to-femoral bypass

Preload reduction

Nitroglycerin

Controlled phlebotomy

Atrial

-to-femoral bypass

Renal protection

Fluid administration

Distal aortic perfusion techniques

Selective renal artery perfusion

Mannitol

Drugs to augment renal perfusion

Other

Hypothermia

↓ Minute ventilation

Sodium bicarbonate

Slide18

Physiologic Changes with Aortic

Unclamping

Hemodynamic Changes

↓

Myocardial contractility

↓

Arterial blood pressure

↑

Pulmonary artery pressure

↓

Central venous pressure

↓

Venous return

↓

Cardiac output

Slide19

Physiologic Changes with Aortic

Unclamping

Metabolic Changes

↑

Total-body oxygen consumption

↑

Lactate

↓

Mixed venous oxygen saturation

↑

Prostaglandins

↑

Activated complement

↑

Myocardial depressant factor(s)

↓

Temperature

Metabolic acidosis

Slide20

Therapeutic Interventions

↓

Inhaled anesthetics

↓

Vasodilators

↑

Fluid administration

↑

Vasoconstrictor drugs

Reapply cross-clamp for severe hypotension

Consider

mannitol

Consider sodium bicarbonate

Slide21

ANESTHETIC MANAGEMENT

Intraoperative

monitoring

The potential for

significant

and

rapid blood loss

can not be underestimated

Internal jugular

catheter and one or two large-bore peripheral catheters

Arterial catheter

should be routine in all patients undergoing aortic reconstruction (

radial artery

)

A

noninvasive blood pressure cuff

should be placed on the arm

contralateral

to the arterial catheter

A

central venous catheter

should be used for

all

open aortic procedures (

monitoring of central venous pressure and administration of drugs

)

Slide22

ANESTHETIC MANAGEMENT

Intraoperative

monitoring

Pulmonary artery catheter

Significant left ventricular dysfunction

(ejection fraction <30%),

A history of congestive heart failure

Significant renal impairment

(

creatinine

>2.0 mg/dl)

Cor

pulmonale

Two-dimensional TEE

has been used

intraoperatively

to assess :

Global ventricular function

Guide fluid therapy

Monitor for myocardial ischemia

Reveal abnormalities in left ventricular wall motion

Wall thickening

Slide23

ANESTHETIC MANAGEMENT

Autologous

Blood Procurement

Routine

crossmatching

of 4 to 6 units of packed red blood cells

Preoperative

autologous

donation,

Intraoperative

cell salvage

Acute

normovolemic

hemodilution

Slide24

ANESTHETIC MANAGEMENT

Anesthetic Drugs and Techniques

A variety of anesthetic techniques:

General Anesthesia

Regional

(

epidural

)

Anesthesia

Combined

techniques

Slide25

ANESTHETIC MANAGEMENT

induction

Variety of intravenous anesthetics (

Thiopental

,

Etomidate

,

Propofol

) are suitable.

The addition of a short-acting, potent

opioid

such as

Fentanyl

(3 to 5

μg

/kg) usually provides stable

hemodynamics

during and after induction.

Volatile

anesthetics

may be administered in low concentration before intubation during assisted ventilation as an adjunct to blunt the

hyperdynamic

response to

laryngoscopy

and

endotracheal

intubation.

Esmolol

(10 to 25 mg),

Sodium

nitroprusside

(5 to 25

μ

g),

Nitroglycerin

(50 to 100

μ

g), and

Phenylephrine

(50 to 100

μg

) should be available for bolus administration during induction if needed to maintain appropriate

hemodynamics

.

Slide26

ANESTHETIC MANAGEMENT

Maintenance

of Anesthesia:

Vital Organ perfusion and function by the provision of Stable

Perioperative

Hemodynamics

is

more important

to overall outcome than the choice of anesthetic agent or technique is

Slide27

ANESTHETIC MANAGEMENT

Maintenance of anesthesia

a combination of a potent

opioid

(

Fentanyl

or

Sufentanil

)

and an inhaled anesthetic

(

Sevoflurane

,

Desflurane

,

or

Isoflurane

)

Balanced

Anesthesia

Slide28

ANESTHETIC MANAGEMENT

Nitrous oxide

can be used to supplement either an

opioid

or an inhaled anesthetic.

In general,

nitrous oxide

DECREASES

CO

and

ABP

while

INCREASING

SVR

Slide29

ANESTHETIC MANAGEMENT

Combined General-Epidural Anesthesia

Four randomized trials, with nearly 450 combined patients undergoing aortic reconstruction,

failed

to demonstrate a

REDUCTION

in the incidence of

perioperative

intraoperative

, or postoperative

myocardial ischemia

when epidural techniques were used.

Additionally, randomized trials

Have Not

demonstrated a reduction in the incidence of

cardiovascular

,

pulmonary

, or

renal

complications after aortic surgery with the use of epidural techniques

.

Slide30

ANESTHETIC MANAGEMENT

Combined General-Epidural Anesthesia

Physiologic derangements incurred during the

perioperative

period

Depression of consciousness

Hypothermia

Fluid overload

Incisional

pain

Ileus

Respiratory depression

less common, but more severe postoperative complications

Mi

Pneumonia

Sepsis

Renal failure

Decreased tissue perfusion

Slide31

ANESTHETIC MANAGEMENT

Combined General-Epidural Anesthesia

Thus, if

perioperative

care

and

pain relief

are optimized, epidural anesthetic and analgesic techniques for aortic surgery offer no major advantage or disadvantage over general anesthesia and intravenous patient-controlled analgesia.

Slide32

ANESTHETIC MANAGEMENT

Emergence From Anesthesia

Should be conducted after restoration

of

circulation

and establishment of adequate organ

perfusion

Hemodynamic

,

metabolic

, and

temperature

homeostasis

must be achieved before skin closure

Otherwise, patients are transported to the intensive care unit (

ICU

) with their trachea

intubated

and their ventilation controlled

Slide33

ANESTHETIC MANAGEMENT

Emergence From Anesthesia

At the start of skin closure,

Inhaled Anesthetics are discontinued,

Nitrous Oxide

is increased to 70%,

and any residual neuromuscular blockade is

reversed.

A large nasal airway

can be inserted after induction but before systemic

heparinization

in all patients for whom

extubation

is planned in the operating room.

Slide34

ANESTHETIC MANAGEMENT

Emergence From Anesthesia

Hypertension and tachycardia are aggressively controlled during emergence by the use of

short-acting agents such as

Esmolol

,

Nitroglycerin

, and

Sodium

nitroprusside

Patients are placed in a

recumbent

,

head-up position

, and nitrous oxide is discontinued.

If

spontaneous

ventilation is adequate, the trachea is

extubated

.

Some centers advocate

extubation

of all patients in the ICU after a period of

stability

has been established. In these cases, mild sedation with a

benzodiazepine

such as

midazolam

is appropriate

Slide35

ANESTHETIC MANAGEMENT

Temperature Control

Normothermia

should be maintained

Increasing ambient temperature in the operating room

Applying warm cotton blankets

And warming intravenous fluids

A forced-air warming blanket should be applied over the

upper

part of the body.

The

lower

part of the body should

not

be warmed because doing so can increase injury to ischemic tissue

distal

to the cross-clamp by increasing metabolic

demands

.

Slide36

Thoracoabdominal

Aortic Aneurysms

(

TAA

)

Slide37

Aneurysms of the

thoracoabdominal

aorta occur primarily because of

atherosclerotic degenerative disease (80%)

Chronic aortic dissection (17%)

The remainder are caused by either

Trauma

Connective tissue diseases involving the aortic wall from conditions such as

Marfan’s

syndrome,

Cystic medial degeneration,

Takayasu’s

arteritis

,

Syphilitic

aortitis

.

Slide38

The Crawford Classification

Slide39

Slide40

Preoperative Preparation and Monitoring

Before the day of surgery, the anesthesiologist and vascular surgeon should discuss, at a minimum, the following issues:

Extent of the aneurysm and technique of surgical repair,

Plans for distal aortic perfusion,

Monitoring for spinal cord ischemia,

Renal and spinal cord protection,

Hemodynamic monitoring,

Ventilation strategy.

Slide41

Radial

and

femoral

arterial pressure should be simultaneously displayed on the

Anesthesiologist’s Monitor

and a monitor visible to the

surgeons and the

perfusionists

Slide42

A

double-lumen

endobronchial

tube should be inserted for the purpose of

one-lung ventilation

A

left-sided

endobronchial

tube is optimal

Many centers use

electrophysiologic

monitoring with

somatosensory

evoked potentials (

SSEPs

) or motor evoked potentials (

MEPs

) to monitor for

spinal

cord

ischemia

Body temperature

should be monitored at two sites (

core

and

peripheral

) to assess cooling and warming when

bypass techniques

are used.

Deep Hypothermic Circulatory Arrest

Slide43

Slide44

Anesthetic Management

Anesthetic Technique

There is no single best anesthetic technique for TAA repair.

Usually, balanced anesthesia is provided with a combination of an

opioid

, a low-dose potent

volatile

anesthetic, a

benzodiazepine

, and a

long-acting muscle relaxant.

A

total intravenous

technique may be optimal if

transcranial

MEP monitoring is used

Extubation

should always take place in the

ICU

and only after a significant period of hemodynamic and metabolic stability.

Slide45

Spinal Cord Ischemia and Protection

Paraplegia is a devastating complication of aortic surgery.

The incidence of paraplegia is reported to be :

0.5% to 1.5% for

coarctation

repair,

0% to 10% for thoracic aneurysm repair,

10% to 20% for

thoracoabdominal

repair

as high as 40% for extensive dissecting TAA repair.

Slide46

Slide47

CSF drainage

is frequently used to improve spinal cord perfusion during TAA repair and is often used in combination with distal aortic perfusion.

Potential complications include :

headache

,

meningitis

,

chronic

CSF

leakage

, spinal or epidural

hematoma

, and subdural hematoma.

Slide48

Hypothermia

is probably the

most

reliable method of

neuroprotection

from ischemic injury.

By reducing

oxygen

requirements by approximately

5%

for each degree centigrade, a

twofold

prolongation of tolerated cross-clamp time is achieved by cooling even to mild hypothermia (

34°C

).

Regional

cooling is beneficial in humans who received

epidural

infusions of

4°C saline.

Slide49

A variety of

drugs

have been studied in an attempt to reduce the incidence of ischemic spinal cord injury:

Barbiturates

Corticosteroids*

Calcium channel blockers

N-methyl-d-

aspartate

receptor antagonists

Magnesium

Naloxone

*

Intrathecal

papaverine

*

Slide50

Delayed-onset neurologic deficits

Preoperative

renal dysfunction

,

acute dissection

, and extent

type II TAA

are significant predictors of delayed neurologic deficit.

Postoperative

hypotension

and

CSF drain malfunction

may play an important role in the development of these deficits.

In one report,

57%

of patients recovered neurologic function with

optimization

of

blood pressure

and

CSF drainage

Slide51

Renal Ischemia and Protection

Renal failure after TAA repair results from:

preexisting renal dysfunction

,

ischemia

during cross-clamping,

thrombotic

or

embolic

interruption of renal blood flow, and

hypovolemia

and

hypotension

.

Approximately

6%

of patients require postoperative

dialysis

, even in centers with the most clinical experience.

The associated

mortality

can be

high

.

The

duration

of cross-clamp time is very important

Slide52

Retrograde distal aortic perfusion techniques

Adequate bypass

flow

and

arterial

blood

pressure

Systemic and regional

hypothermia

Some centers advocate the use of DHCA

Mannitol

Loop diuretics

Dopamine given in low doses (3

μg

/kg/min)

At the present time, optimal renal protection during TAA surgery should rely on

hypothermia

,

mannitol

, and

prevention

of

hypotension

and

hypoperfusion

of the kidneys.

Slide53

Coagulation and Metabolic Management

Coagulopathy

is a

frequent

complication during TAA repair.

A

dilutional

coagulopathy

Residual

heparin

Ischemia

of the

liver

Persistent

hypothermia

Slide54

With the

early

use of

FFP

and

platelets

, severe

coagulopathy

can often be avoided

The

PT

,

PTT

,

fibrinogen

level, and

platelet

count should be measured

frequently

Cryoprecipitate

(

hypervolemia

, PT &PTT rise)

When

coagulopathy

persists

despite these efforts,

ε-

aminocaproic

acid

is beneficial as

antifibrinolytic

therapy, and

desmopressin

Normothermia

should be achieved by complete

rewarming

before separation from bypass

Arterial blood gases

and

electrolyte

levels should be measured frequently

Sodium bicarbonate

Hyperkalemia

(Calcium chloride and sodium bicarbonate)

Coagulation and Metabolic Management

Slide55

Endovascular Aortic Repair

less invasive alternative to open abdominal aortic aneurysm repair and to provide a treatment option for patients considered to be poor surgical candidates

Interest in

endoluminal

aortic grafting has expanded to include disease of the thoracic and

thoracoabdominal

aorta.

Slide56

Slide57

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Slide59

Slide60

Slide61

The endovascular approach can be undertaken without the

LARGE INCISIONS

EXTENSIVE DISSECTIONS

PROLONGED AORTIC CROSS-CLAMP TIMES

SIGNIFICANT BLOOD LOSS

FLUID SHIFTS

associated with open repair

Slide62

Anesthetic Management

Local

,

regional

, and

general

anesthesia

techniques have all been described for endovascular aortic repair shortly after its introduction

.

Slide63

Anesthetic Management

A variety of regional techniques have been used, including

PARAVERTEBRAL

SPINAL

CONTINUOUS SPINAL

EPIDURAL

COMBINED SPINAL/EPIDURAL

Slide64

A sedation technique using

dexmedetomidine

with local anesthesia has been reported

Slide65

The use of local or regional anesthesia may reduce

ICU admission

Hospital length of stay

Early complications

Mortality benefit

Slide66

As with open aortic repair,

maintenance of vital organ perfusion

and function by the provision of

stable

perioperative

hemodynamics

is probably more important to overall outcome than the choice of anesthetic technique is.

Slide67

I commonly use a

general anesthetic

technique for endovascular aortic repair in patients requiring

extensive

groin dissection or any

retroperitoneal

dissection

and those requiring

complex

repairs, where conversion to open repair may be more likely.

A

balanced

technique using relatively

short-acting

agents maximizes management flexibility.

Opioid

requirements are usually

minimal

(2 to 4

μg

/kg

fentanyl

), and postoperative pain is easily managed.

Esmolol

,

sodium

nitroprusside

,

nitroglycerin

, and

phenylephrine

should be available and used to maintain appropriate

hemodynamics

.

Epidural and spinal anesthesia is used selectively based primarily on

patient

and

surgeon

preference

.

Slide68

MONITORING

Placement of a

radial artery catheter

should be

routine

for all endovascular aortic repairs

It should be placed on the

right

side because a catheter may be placed

percutaneously

in the

left

brachial artery for aortic

angiography

.

Central venous and pulmonary artery catheter monitoring is

not

routine

.

Two

large-bore peripheral intravenous catheters are recommended

The potential for rapid blood loss is real

Slide69

MONITORING

Catheterization of the

bladder

Fluid

management is directed primarily at maintaining

normovolemia

.

Isotonic

bicarbonate

infusion is often used in patients with

renal

dysfunction

to reduce the incidence of

contrast-induced

nephropathy

TEE

monitoring is frequently used

Intraoperative

spinal

evoked

potential

monitoring plus temporary (

15

minutes

) balloon

occlusion

of the thoracic aorta before stent-graft deployment

Slide70

Endovascular repairs involving the

descending

thoracic aorta require additional preparation and monitoring.

These procedures are often performed in the

operating

room

under

general

anesthesia

.

spinal cord ischemia

Postoperative

hypotension may play a role as well

Delayed paraplegia

10

months

after endovascular repair of thoracic aortic aneurysms has been reported.

CSF

drainage

has been shown to reverse

delayed-onset

neurologic deficit after endovascular TAA repair

Slide71

Carotid

Endarterectomy

The principal cause of carotid artery occlusive disease is

atherosclerosis

, which most commonly involves the

bifurcation

of the common carotid artery with frequent extension into both the internal and external carotid arteries.

Slide72

Carotid

Endarterectomy

The

clinical manifestations

of carotid artery disease represent a spectrum of conditions, with fatal or debilitating

stroke

secondary to cerebral infarction at one end of the spectrum and ranging successively through

nondebilitating

stroke,

transient

ischemic

attack

, and

amaurosis

fugax

(transient attack of monocular blindness) to an asymptomatic

bruit

There are well-defined

risk

factors in patients with stroke, the

most

important

of which is

hypertension

Slide73

Carotid

Endarterectomy

The only approved therapy is intravenous

recombinant tissue

plasminogen

activator

Slide74

Carotid

Endarterectomy

Carotid

endarterectomy

is the most common peripheral vascular surgical procedure performed in the United States, with an estimated

130,000

procedures performed annually.

Slide75

Perioperative

Morbidity and Mortality

Neurologic deficits

occur most commonly in patients with poorly controlled

preoperative

hypertension

or in those with

hypertension

or

hypotension

postoperatively

More than

half

of these deficits occur more than

4 hours

postoperatively

The incidence of

perioperative

MI

in patients undergoing carotid

endarterectomy

ranges from

0% to 4%

MI

is the

leading

cause

of both

perioperative

and late mortality after carotid

endarterectomy

Slide76

Preoperative Evaluation

CAD

is common in patients undergoing carotid

endarterectomy

Preoperative studies are

rarely

needed for the evaluation of

myocardial function

or

ischemic potential.

Exceptions

Unstable angina,

Recent MI with evidence of ongoing ischemia,

Decompensated

congestive heart failure,

Significant

valvular

disease

Slide77

Patients with both

severe CAD

and

severe carotid

artery occlusive disease represent somewhat of a management dilemma

Preoperative Evaluation

Slide78

Anesthetic Management

Anesthetic management goals for carotid

endarterectomy

include:

Protection of the heart and brain from ischemic injury

Control of the heart rate and blood pressure

Ablation of the surgical pain and stress responses

To have an awake patient at the end of surgery for the purpose of neurologic examination

Slide79

Anesthetic Management

The

preoperative visit

is particularly important in patients undergoing carotid surgery

During this visit

A

series

of blood pressure and heart rate measurements are obtained from which acceptable

ranges

for

perioperative

management can be determined

Patients are instructed to

continue

all long-term

cardiac

medications

up to and including the morning of surgery

Unless contraindications exist,

aspirin

therapy should be continued throughout the

perioperative

period

Slide80

Anesthetic Management

Routinely monitor

leads II

and

V5

for detection of rhythm disturbances and

st

-segment

changes

On-line

st

-segment analysis is particularly helpful and is used

An

intra-arterial

catheter for beat-to-beat blood pressure monitoring is placed in

all patients

Central venous and pulmonary artery catheters are usually

unnecessary

for carotid surgery

If such monitors are used, the

subclavian

or

femoral

insertion sites are most practical

Slide81

Intravenous access for fluid and drug administration can be accomplished with a

single

,

secure

,

medium-bore

(

16

-gauge) catheter

After placement of

routine

monitors

and administration of

oxygen

by facemask, a

sufentanil

infusion (0.5 to 1.0

μg

/kg) is initiated

If the patient becomes at all sedated during the planned

10-

to

15-minute

infusion period

Induction of anesthesia is accomplished with incremental doses of

thiopental

(≤8 mg/kg) followed by

succinylcholine

, unless contraindications exist

Anesthetic Management

Slide82

Administration of

fluids

intravenously (

5

mL

/kg

), careful

titration

of anesthetics, and

immediate

treatment of

hypotension

are especially important

Anesthesia is maintained with

50%

nitrous

oxide

in oxygen and low-dose (i.e., less than half the minimum alveolar concentration)

potent

inhaled

anesthetics

Isoflurane

is preferred because fewer

ischemic

electroencephalographic (

EEG

) changes occur during carotid occlusion

Esmolol

,

Phenylephrine

, Nitroglycerin, Sodium

Nitroprusside

Anesthetic Management

Slide83

Arterial

blood

pressure

should be maintained in the

high-normal

range throughout the procedure and particularly during the period of

carotid

clamping

in an attempt to

increase

collateral

flow

and

prevent

cerebral

ischemia

induced

hypertension

to approximately

10

% to

20

% above

baseline

is advocated during the period of carotid clamping when

neurophysiologic

monitoring

is

not

used

The Risk For

Myocardial

Ischemia

Or

Infarction

Anesthetic Management

Slide84

Surgical

manipulation

of the

carotid

sinus

with activation of the

baroreceptor

reflexes

can cause abrupt

bradycardia

and

hypotension

Cessation

of surgical manipulation promptly restores the

hemodynamics

, and

infiltration

of the

carotid

bifurcation

with

1%

lidocaine

usually prevents further episodes.

Infiltration may, however, increase the incidence of both

intraoperative

and

postoperative

hypertension

I do

not

advocate

routine

infiltration of the carotid bifurcation

Anesthetic Management

Slide85

With closure of the deep

fascial

layers

Isoflurane

is discontinued

Nitrous oxide is increased to 70%

Ventilation is controlled manually

On application of the surgical dressings

Neuromuscular reversal agents are administered

Oxygen is increased to 100%

Decrease external stimuli to the patient

Quieting the room

Turning off the overhead surgical lights

Placing the patient in a head-up recumbent position

Ventilation is gently assisted

Until spontaneous eye opening or movement

All patients are

extubated

after neurologic integrity is established

Anesthetic Management

Slide86

Neurologic deficits on emergence require immediate discussion with the surgeon about the need for

angiography

,

reoperation

, or

both

Anesthetic Management

Slide87

Regional anesthesia is accomplished by blocking the

C2 to C4

dermatomes

Superficial

And

Deep

Cervical Plexus Block

Regional and Local Anesthesia

Slide88

Regional and Local Anesthesia

Slide89

Regional anesthesia allows

continuous

neurologic

assessment

of

awake

patients, which is believed to be the

most

sensitive

method for detecting inadequate cerebral perfusion and function

Other advantages that have been reported include

Avoidance of expensive cerebral monitoring

Reduced need for shunting

Greater stability of blood pressure

Decreased

vasopressor

requirements

Reduced hospital costs

Regional and Local Anesthesia

Slide90

Requires significant patient

cooperation

throughout the procedure

With constant

communication

Gentle

handling of tissues

Supplemental

infiltration of local anesthetic by the surgeon, especially at the

lower border and

ramus

of the mandible

Sedation

(must be kept to a minimum)

Levels of consciousness

Speech

Contralateral

handgrip

(

Squeaky toy)

The surgical drapes are “

tented

” over the head and face area to minimize

claustrophobic anxiety

.

Regional and Local Anesthesia

Slide91

Slide92

No absolute contradiction

to regional anesthesia for carotid

endarterectomy

exists

Avoid regional anesthesia under the following circumstances:

Strong

preference

for general anesthesia expressed by the patient (

i.E.

,

Claustrophobia

)

Language

barriers that make communication difficult

Difficult

vascular anatomy

Slide93

Regional versus General Anesthesia

Increased incidence of

perioperative

stroke

and

cardiopulmonary

complications

in patients under

general anesthesia

Slide94

Regional versus General Anesthesia

Inability to use pharmacologic cerebral protection with anesthetics

Patient panic or loss of cooperation

Seizure or loss of consciousness with carotid clamping

Inadequate access to the airway

Serious complications from a cervical plexus block is low

Near-toxic levels of local anesthetic

Phrenic

nerve paresis is common after cervical plexus block

Slide95

Regional versus General Anesthesia

The ultimate decision to use one technique over the other must be based on

The surgeon’s experience

The anesthesiologist’s experience

The patient’s preference

Slide96

Carbon Dioxide and Glucose Management

Hypercapnia

may cause a “

steal

” phenomenon (i.e., shunting of blood away from

hypoperfused

territories with dilated vasculature) and is generally avoided

Hypocapnia

, with its associated cerebral vasoconstriction, has been advocated to promote a

reversal

of this steal phenomenon

However, there is

little

clinical

evidence

for this “reverse” steal effect

It is therefore common practice to maintain

normocapnia

or

mild

hypocapnia

during carotid

endarterectomy

Slide97

Carbon Dioxide and Glucose Management

There is evidence of increased

ischemic

injury to neural tissue when ischemia occurs in the presence of

hyperglycemia

It may be beneficial to maintain a blood glucose level

below 200 mg/dl

in patients undergoing carotid

endarterectomy

If

hyperglycemia

is treated with

insulin

preoperatively or

intraoperatively

, the blood glucose level should be carefully

monitored

, especially during

general

anesthesia

, to avoid the dangers of

hypoglycemia

Slide98

Postoperative Management

Of Vascular Surgery Patients

Vascular surgery patients require special attention during the postoperative period because

most cardiac complications

occur postoperatively

Conventional practice is to monitor all vascular surgery patients in an

ICU

setting after surgery

Slide99

Postoperative Management

Of Vascular Surgery Patients

to prevent ischemia β-Blocker and

statin

therapy should be continued throughout the postoperative period

Slide100

Postoperative Management

Of Vascular Surgery Patients

Coagulopathy

, either from residual

heparin

or from

dilutional

coagulopathy

after massive transfusion

Bleeding

through fresh vascular

anastomoses

may occur when significant postoperative

hypertension

is untreated

Hypovolemia

occurs after aortic surgery as a result of significant

third-space fluid loss

and

bleeding

Hypovolemia

may lead to

hypotension

and

hypoperfusion

of the coronary arteries or lower extremity vascular grafts.

Graft occlusion in the lower extremities occurs

in 3%

to

10%

of patients

Lower extremity

pulses

should be checked at

hourly

intervals.

Some patients require the administration of

heparin

or

dextran

to prevent

thrombosis

Slide101

Residual hypothermia

in the early postoperative period is associated with an increased incidence of

myocardial ischemia

Even

mild

hypothermia of approximately

35°C

is associated with

a 200%

to

700%

increase in

norepinephrine

levels, generalized

vasoconstriction

, and

increased blood pressure

in postoperative patients

Shivering

occurs and increases

total-body

oxygen consumption

Postoperative Management

Of Vascular Surgery Patients

Slide102

It is important to control the

stress response

in the postoperative period

pain

anemia

hypothermia

Hemodynamic extremes

ventilatory

insufficiency

I

n

mechanically ventilated patients, the

weaning

period is especially

stressful

, and myocardial ischemia occurs frequently during this time

Postoperative Management

Of Vascular Surgery Patients

Slide103

High incidence of

coexisting

disease

Clinical studies provide insight into the preoperative assessment and optimization of

Cardiac risk

The implications of anesthetic technique

The diagnosis, prevention, and treatment

of myocardial ischemia in vascular surgery patients

Postoperative Management

Of Vascular Surgery Patients

Slide104